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MEPS
Marine Ecology Progress Series

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MEPS 424:259-271 (2011)  -  DOI: https://doi.org/10.3354/meps08987

Persistent decline in abundance of harbor seals Phoca vitulina richardsi over three decades in Aialik Bay, an Alaskan tidewater glacial fjord

Anne Hoover-Miller1,2,*, Shannon Atkinson3, Suzanne Conlon1, Jill Prewitt1, Peter Armato2,4

1Alaska SeaLife Center, Seward, Alaska 99664, USA
2School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
3Juneau Center School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, Alaska 99801, USA
4Ocean Alaska Science and Learning Center, National Park Service, Seward, Alaska 99664, USA

ABSTRACT: Glacial ice calved from tidewater glaciers in Alaska provides an important haulout habitat for harbor seals Phoca vitulina richardsi, and its extent and ecological influence is being reduced by climate change. The number of harbor seals using glacial ice adjacent to Aialik Glacier, central Gulf of Alaska, declined by 93% from 1979 to 2009. During this time, seals demonstrated variability in their selection of haulout locations, particularly during the molt. Near Pedersen Glacier, 6 km south of Aialik Glacier, the number of seals doubled from 2005 to 2007; this was followed by an equivalent loss from 2007 to 2009. This influx, which occurred during a period of cold marine conditions, was associated with the arrival of seals from locations outside Aialik Bay, rather than from movements of seals from Aialik Glacier. Nearly all pups were born near Aialik Glacier. Pup production, which was stable from 1979 to 1983, subsequently declined by 12.4% yr–1 through 1994. Although the rate of decline abated, the numbers of pups continued to decline by 4.6% annually from 1994 to 2009. The persistent decline of harbor seals in Aialik Bay is similar to that observed in Glacier Bay, southeast Alaska, but contrasts with trends at nonglacial sites in the Gulf of Alaska and southeast Alaska where populations have been increasing since the mid-1990s. Results indicate flexibility in selection of haulout location and potentially the proportion of time seals are present on the ice. The persistent decline in pup production, however, raises concern over the future of harbor seals in previously important glacial pupping habitats and the integrity of unique glacial fjord ecosystems.


KEY WORDS: Harbor seal · Phoca vitulina richardsi · Glaciers · Population decline · Gulf of Alaska


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Cite this article as: Hoover-Miller A, Atkinson S, Conlon S, Prewitt J, Armato P (2011) Persistent decline in abundance of harbor seals Phoca vitulina richardsi over three decades in Aialik Bay, an Alaskan tidewater glacial fjord. Mar Ecol Prog Ser 424:259-271. https://doi.org/10.3354/meps08987

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